Windows XP users who upgrade their hard drives in the coming year might be faced with a big issue; the format of hard drives is soon to undergo a massive upgrade. The new format will completely change the way the drives store data which users save on them.

For the last thirty years, hard drives have been formatted using blocks of 512 bytes. This technology became very popular when IBM started using it as the default formatting method for its floppy disks. In an age when hard drives were just a few MB in size, the 512 byte blocks were really useful for formatting the disks.

But with drives now exceeding a terabyte in storage space, such small blocks are no longer practical. Such fine blocks not only slow down the data storage speed, but also waste a lot of space. Each 512 byte sector starts with a marker and then it has an area that stores error correction codes. Then there is a tiny gap before the next sector starts. The larger the drive, more the amount of storage space occupied by these gaps and thereby wasted.

Under the new advanced format, the sectors will be increased to 4K each. This should cut down on wasted space by as much as eight times. Compared to the 512 byte block size, hard drives will also be able to allot more space per block for error correction. With the new format, hard drives will become more reliable; manufacturers too will be able to create bigger and faster drives that consume lesser power.

They will also be able to make better use of the space available on the hard drives. “We can put more data on the disk," Steve Perkins, a technical consultant for Western Digital said. “It's about 7-11% more efficient as a format."

All hard drive makers have already committed to moving to the new 4K advanced format by the end of January 2011; the International Disk Drive Equipment and Materials Association (IDEMA) is also actively working towards making this happen.

While the new format brings many advantages, it is also a potential headache for users of older operating systems, primarily Windows XP. Microsoft’s most successful OS was released prior to the finalization of the 4K format. So the system does not support it.

On the other hand, newer OS versions including Windows 7, Windows Vista, OS X Tiger, Leopard, Snow Leopard, and all post-September 2009 versions of Linux are 4K ready. To overcome this issue with Windows XP, manufacturers have come up with a possible solution; all advanced format drives will continue to emulate 512 byte sector size just for this OS.

This would make it possible for Windows XP to read data from the new drives without any issues. However, the same cannot be said about writing data. In certain instances, the drive will have to go through two steps to write data instead of one. This would mean a delay of about 5 milliseconds in writing. To ensure this delay is kept down to the minimum, hard drive manufacturers are working on creating software that aligns the 512 sectors with the 4K ones.